Fuel pumps for internal combustion engines are used to deliver fuel from a fuel tank to a carburetor. These fuel pumps are frequently mounted in the fuel tanks of the vehicle and therefore are manufactured to sustain a wide range of ambient temperatures.
Generally, fuel pumps are powered by an electric motor having an armature mounted inside the fuel pump housing. A pumping mechanism, such as a positive displacement type, is coupled to the armature of the electric motor and draws fuel through an inlet port and pumps the fuel to an outlet port. The pumping mechanism and electric motor, enclosed within the pump housing, generate heat within the housing and is cooled by the fluid fuel flowing through the pump housing. If the vehicle has been operating for a period of time with no fluid flow in the system, the heat generated by the pumping mechanism and electric motor is trapped within the pump housing by the pump outlet valve and can potentially cause damage to the electric motor.
The problem which has been observed occurs when the engine is running but there is no net flow of fluid through the pump. The engine may run on due to residual pressure in the lines from air and vapor. Meanwhile, the pump may be running but there is no net cooling flow resulting from the flow of liquid fuel. The proposed valve is sensitive to this condition and opens automatically when the internal pump pressure drops. A conventional ball-type valve will not always open, thus causing an overheat condition.